Radio appliance



April 17, 1928. 1,666,505

J. M. PETERSON RADIO APPLIANCE Filed Feb. 28 1927 am, wszm Patented Apr. .17, 1928.

UNITED STATES ISBN 16:. rn'rnnson, or MILWAUKEE, WISCONSIN.

RADIO APPLIANCE.

Application filed February 28, 1927. Serial No. 171,612.

This invention relates to certain new and useful improvements in radio appliances and refers more particularly to an appliance adapted for use with the usual radio broadcast receiver whereby the same is enabled to reach wave lengths ,without its ordinary range.

Heretofore, it has been customary to supply sets of radio frequency transformers having different values of inductance and different wave length ranges which were plugged in the receiver in place of the usual set of radio frequency transformers having a normal usual range offrom two hundred to six hundred meters. This method of adapting an ordinary receiver for wave lengths either lower than two hundred or higher than six hundred meters required special design, in that the usual methods of stabilizing the radio frequency stages is not efiicient when used with radio frequency transformers of different inductance values having different wave length ranges.

Therefore, this invention has for one of its objects the provision of means whereby any radio broadcast receiver may be readily adapted to receive signals at wave lengths without its normal range.

Another object of this invention resides in the provision of a simple device having a plug adapted to be inserted in one of the tube sockets of the receiver with which the device is to be used to convert the same into a receiver of different wave receiving capacity.

With the above and other objects in view which will appear as the description proceeds, my invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claim, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claim.

In the accompanymg drawing, I have illustrated one complete example of the physical embodiment of my invention constructed according to the best mode I have so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a perspective view of my 1m-. proved appliance;

Figure 2 is a front elevational view of; my improved appliance illustratmg the man-.-

ner of connecting the same with a, radio broadcast receiver, and

Figure 3 is a schematic wiring diagram of an ordinary five tube tuned-radio frequency circuit and of my improved appliance illustrating the manner of connecting the same in the circuit of the receiver.

Referring now more particularly to the accompanying drawing, in-which like numerals designate like parts throughout the several views, the numeral 5 designates a receiver housing or cabinet having a front panel 6 and a top panel 7, a tuning dial 8 having a vernier adjustment 9 and a control knob 10 being mounted on the exterior of the panel 6 for controlling the receiver proper, as will be later described.

The top panel 7 has a plurality of apertures 11 therein which are spaced'and of a size to conform with the universal vacuum tube socket of conventional type through which the prongs of a'tube 12 are adapted to be engaged with the contacts of a suitable socket (not shown). A grid leak 13 is mounted on clips.14 secured to the top panel 7, and springconnector clips 15 are secured to the top panel at each side, as illustrated, to provide means for" attaching an antennalead 16 and a ground lead 17, as illustrated in Figure 2. Extended through an aperture '(notshown) in the back of the 'cabinet 5 is a cable 18 having a plug 19 secured to its end which is provided with a plurality of prongs 20.

The method of applying my improved attachment or wave changer to a radio broadcast receiver is illustrated in Figure 2, in which the attachment is shown connected with a radio receiver of the tuned radio frequency type usually employing five tubes, two radio frequency tubes 21, a detector tube and two audio frequency amplifier tubes 22. The detector tube may be used as the tube 12, being removed from the receiver and the plug 19 inserted in its place enabling the receiver to reach the wave lengths for which this particular appliance is designed, and which will now be described.

The component units of my device have not been shown in detail as they maybe standard and as their details of construction form no part of this invention, their description is limited to the schematic showing in Figure 3. As clearly depicted in this diagram, my device conslsts of an antenna coupler coil 23 having a primary 24 connected with the antenna 25 through a high resistance 26, the resistance being included to preventinterference from antenna harmonics, and the other side of the primary 24: going to the ground as customary. The secondary winding 26 is in inductive relation with the primary 24 and is tuned by a condenser 27 manipulated by means of the dial 8 and the Vernier 9. Regeneration i's added by means of a tickler coil 28 and is regulated by asmall variable condenser 29 which is controlled by the knob 10. The usual grid condenser 30 cooperates with the grid leak 13 as is customary.

The cable 18 by which the attachment is connected with the receiver contains three conductors 32, 33 and 34 which terminate in prongs 32, 33' and 34', respectively, similarto the prongs of a vacuum tube and which constitute the prongs 20, the fourth prong of which has no function. The conductor 32 connects the out-put of the attachment or in other words the plate of the tube 12 with the plate terminal 35 of the detector tube socket, thereby passing the signal received'and detected by my appliance onto the first audio frequency transformer 36, the first audio frequency tube 22, the second audio frequency transformer 37, and

through the last tube 22 to the speaker or phones (not shown) connected with the terminals 38 in the conventional manner. Connected in series with the out-put of the plate of the tube 12 and the conductor 32 is a high resistance 39 which functions as a choke coil to keep the radio frequency currents out of the audio frequency amplifier.

The other two conductors 33 and 34, by means oftheir respective prongs 33nand 34, connect the filament of the tube 12 with the filament terminals 40 and 41 of the detector tube socket to supply the necessary cur rent to the tube filament. 7

From this it will be seen that when my attachment is used with a. receiver of the type described, (a tuned-radio frequency, a neutrodyne, or the like), the stages of radio frequency amplification ahead of the detector are automatically cut out of the circuit by the insertion of the plug 19 in the detector tube socket, the grid of the detector tube socket being left open and thus all tuning is accomplished by means of the condenser 27 actuated by the dial 8. 2

My appliance may also be used in connection with receivers of the super-heterodyne type and when so used the plug 19 is placed in the socket of the tube commonly known as the first detector, the tube 12 then functioning as an oscillator detector, i. e., the one tube performs the functions of both the oscillator and the first detector.

From the foregoing description taken in connection with the accompanying drawing it will be readily apparent to those skilled in the art to which an invention of this character appertains that 1 have provided an appliance which may be readily connected with a radio broadcast receiver having a fixed wave length range whereby the same may be utilized to receive signals at either lower or higher wave lengths.

What- I claim as my invention is: A device of the class described comprising a receiving circuit including a grid leak, and adapted to be connected with a radio broadcast receiver .to change its normal wave length range, a casing for the circuit having a top and front, means mounted on the front of the casing for tuning the circuit, means mounting the grid leak from the top of the casing, means carried by the top for readily releasably connecting an antenna, and a ground wire with the circuit, and a flexible cable extended from the casing whereby the circuit is connected with the circuit of the broadcast receiver.

In testimonywhereof I hereunto aflix my signature.

JOHN M. PETERSON. 

